A limited flexibility seems to be the modern preference. It makes sense. I’ve been involved with parishes where the seating was theoretically 100% flexible, but in practice, a certain fatigue sets in. Having a regular pattern is a good thing.

§ 87 § There are no universal norms regarding fixed or flexible seating but the diocesan bishop may issue further directives in this area. Many churches have found that a combination of fixed and flexible seating works best to accommodate the various liturgical actions. Ideally, no seat in the nave would be located beyond a point where distance and the lighting level of the sanctuary severely impede the view of and participation in liturgical actions. In earlier periods churches designed for large congregations were limited by engineering constraints. The latest construction and engineering technologies now allow for cost-effective and flexible approaches to designing churches with greater roof spans.